Method of refining sulfate turpentine



Patentea anilx 1949 assure METHOD 01'' am G SULFATE George H.fieGregondnternational-Falls, Minn.

assignor toltllnnesota No Drawing.-

and-Ontario Paper Com- Application June 21, 1941,

' Serial No. "7,879

,1 Q g This invention relates to the treatment oi crude turpentineand'more particularly to a'process or deodorizing-turpntines whieh areobtained as a by-product in the..-manuiacture ct, cellulose according tothe sulfate process, and alsothe; development. of a productoipleasingodor and of high quality. j A iurtherob'iect is the provisionin a method of the character described. of improved steps foreliminating the offensive and obnoxious odor phate pulp, the cellulosematerial to be treated (usually wood chips) ,together with the usualchemicals are'pl'aced in a dig'esterand steam admitted untilthepre'ssure in the digester reaches 110-135 pounds with the consequenttemperature within the digester from-about 335 to 350 1". Heat issuppliedto thecooking vessel or digester by direct supply of steam or byexternal heat; the cooking liquor is then "circulated through thecooking vessel during the cooking operation. In the case of heat withindirect steam the cooking liquor is circulated through the digester andan outside heat exchanger; In the direct heat the steam furnishescirculation by'turbulence within the digester. It is ammmon practice. torelieve steam and other vapors generated in the digester during cookingoperation. Thisremoval is. us'-' ually done as the pressure is'heingincreased in vapors are led into a separating devicewhere the condensedoil layer is removed and then sent to storage and the water layersent towaste. The oil' layer is known as crude sulphate wood turpentine.

Due to the presence sodium sulphide in the cooking liquor a number atexceedingly .maiodorr ous sulphur compounds be iormed Such compounds mayinclude mercaptans, dimercaptans, thio-ethers, sulphoxides. sulphones,sul- (Cl. sz-z) z r phinic acids, sulphonic acids, disulphides.thioaldahydes, thioketones, esters,,amides and other complex sulphur ornonsulphur compounds. Bome'or all of these compounds maybe present 5 inthe crude sulphate turpentine, imparting to it an exceedingly ,oilensiveodor, the removal of which presents the chief problem in producingsulphate wood turpentine 0! a pleasing and marketable odor. It has beenfound that this problem is efficiently solved by the present processwhich is a combination 'of chemical and other steps.

In accordance with one aspect of the present invention, crude sulphateturpentine refined by ll what may be termed a chemical extractionprocess employing a material such as kratt mill green liquor; The kraitpulp mill green liquor is substantially immiscible in crude sulphateturpentine but capable of dissolving, combining with or in some mannerin removing odor producing bodies contained therein.

The process oithe present invention includes intimately contacting thecrude sulphate turpentine with krait mill green liquor or itsequivalent,

permitting the mixture to separate into an upper layer composed ofrefined turpentine and a lower layer composed oi substantially saidgreen liquor and the odor producing bodies contained in the crudesulphate turpentine. The upper layer is withdrawn and subjected tofurther treatment as hereinafter more specifically set forth. The lowerlayer is withdrawn and sent to the krai't mill green liquor storage tankand may be used in the knit process without detriment to such asprocess. 1

In order to disclose the nature of the present invention still moreclearly, an illustrative example will hereinaiter be described. Itshould be clearly understood however, that this is done purely for thepurpose of illustration and is .not to .beconsidered a limitation uponthe spirit of the scope 01' this invention.

Example L-About ten parts of crude sulphate turpentine is stirred withabout five parts of kraft mill green liquor. The krait mill green liquoris preferably added in several increments at a temperature of about toabout F. for about ten minutes. The material is permitted to stand untilthe two layers separate. The lower layer consists of the green liquorand the odor producing bodies and this is withdrawn and maybe returnedto the kraft mill green liquor storage. The upper layer consisting oiturpentine is treated with bleaching material-in water such as tocalcium hypochlorite. The amount of available assume 3 chlorine requiredwill vary from about a to about 12% of the weight of the turtine.Suitable agitation is desirable for mixing of the turpentine and thecalcium hypochlorite then is contacted for sevcral'hours with activatedcarbon. The

activated carbon removes by absorption residual coloring matter in theturpentine. The result of the foregoing treatment is a mild odoredturpentine ready for commercial use. i

I If desired, the turpentine obtained may be subjected to distillation.However, for commercial use the distillation step is not required.

The amount of treating liquor used in refining the crude sulphateturpentine is based primarily on theamount of sulphur compoundscontained in the crude sulphate turpentine. As the sulphur compounds,particularly the mercaptans increase in the crude sulphate turpentine,the amount of treating liquor must be increased to obtain satisfactoryresults.

In the krai't or sulphate process of fiber liberation as heretoforedescribed, the wood chips are heated under pressure inclosed digesterswith an alkaline cooking liquor known as white liquor.

A typical white liquor contains Sodium hydroxide 4.00 cu. it. as NazOSodium sulfide 2.17 cu. ft. as NazO Sodium carbonate .93 cu. ft. as NazOThe composition of the white liquor may vary with difierent woods anddifferent cooking schedules etc. This liquor extracts the lignin andother non-cellulose constituents of the wood and is discharged from thedigester at the end of the cook as a dark liquor known as black liquor.In ordinary sulfate mill practice, the black liquor is concentrated andthe black liquor is then burned or smelted in a furnace with theaddition of sodium sulfate. The organic matter is burned out in thefurnace and the inorganic constituents are recovered which are dissolvedin water to form a make-up liquor known as "green liquor." Thecomposition of green liquor is as follows:

Sodium sulfide 2.19 cu. n. as NazO Sodium hydroxide .32 cu. ft. as NazOSodium carbonate 4.67 cu. it. as NazO The composition of green liquormay vary from mill to mill. This green liquor is used as a base formaking up supplies of white liquor for reuse in the digesters bycausticizing it with lime.

An important feature of the invention resides in the use, as an odorextracting medium, of a solution containing the inorganic constituentsnormally found in the cycle of a krait paper mill, that is one or moreof the constituents of green liquor or white liquor. Such solutions canbe withdrawn from the kraft mill cycle, and when the extraction iscompleted, the spent extracting liquor can be returned to the millcycle.

It will be observed by one skilled in the art that the foregoingspecification is subject to modiflcationsand such variations as comewithin the spirit of the invention are intended to be included in theappended claims.

What is claimed is:

1. A method of obtaining commercially usable turpentine which comprises,separating crude turpentine from vapors removed from a kraft cookingprocess, withdrawing green liquor from the kraft mill cycle and mixingsuch withdrawn liquor with the crude sulphate turpentine, permitting themixture .to stand until separated into two layers, removing the lowerlayer and retuming it to the kraft mill cycle and withdrawing the toplayer as refined sulphate turpentine.

2. A method of refining crude sulphate turpentine to obtain commerciallyusable turpentine which comprises, extracting from said crude sulphateturpentine odor producing compounds with an aqueous solution containingsodium hydroxide, sodium carbonate and sodium sulfide.

, 3. A method of refining sulphate turpentine containing malodorouscompounds which comprises, treating said turpentine with an aqueoussolution containing green li'quor as prepared in a kraft paper mill.

4. A method of refining crude sulphate turpentine containing malodorouscompounds which comprises, adding green liquor'at a temperature of aboutto about F. to the crude sulphate turpentine, permitting the mixture tostand until separated into two layers, removing the upper layer ofturpentine, adding calcium hypochlorite containing from about 4% toabout 12% of available chlorine based upon the weight of the turpentine;and thereafter contacting the turpen- REFERENCES CITED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,493,454 Jobson May 6, 19241,938,693 Gillespie et a]. Dec. 12, 1933 2,283,067 Jennings May 12, 1942FOREIGN PATENTS Number Country Date Great Britain 1910

